Nicotinic alpha 7 receptor agonists EVP-6124 and BMS-933043, attenuate scopolamine-induced deficits in visuo-spatial paired associates learning.

Agonists at the nicotinic acetylcholine alpha 7 receptor (nAChR α7) subtype have the potential to treat cognitive deficits in patients with Alzheimer's disease (AD) or schizophrenia. Visuo-spatial paired associates learning (vsPAL) is a task that has been shown to reliably predict conversion from mild cognitive impairment to AD in humans and can also be performed by nonhuman primates. Reversal of scopolamine-induced impairment of vsPAL performance may represent a translational approach for the development of nAChR α7 agonists.

Bioanalysis of (1R,4R,5S,6R)-4-amino-2-oxabicyclo[3.1.0]hexane-4,6-dicarboxylic acid (LY379268) in rat plasma using derivatization liquid chromatography/mass spectrometry.

Background: (1R,4R,5S,6R)-4-amino-2-oxabicyclo[3.1.0]hexane-4,6-dicarboxylic acid, also known as LY379268, a group II metabotropic glutamate receptor agonist, has been widely used in neuroscience as a model compound in studies evaluating antipsychotic drugs for the treatment of schizophrenia.

Analysis of L-serine-O-phosphate in cerebrospinal spinal fluid by derivatization-liquid chromatography/mass spectrometry.

L-serine-O-phosphate (L-SOP), the precursor of L-serine, is a potent agonist against the group III metabotropic glutamate receptors (mGluRs) and, thus, is of interest as a potential biomarker for monitoring modulation of neurotransmitter release. So far, no reports are available on the analysis of L-SOP in cerebrospinal fluid (CSF). Here a novel method is presented to determine L-SOP levels in CSF employing precolumn derivatization with (5-N-succinimidoxy-5-oxopentyl)triphenylphosphonium bromide (SPTPP) coupled to liquid chromatography/mass spectrometry (derivatization-LC/MS, d-LC/MS).

Addressing the need for biomarker liquid chromatography/mass spectrometry assays: a protocol for effective method development for the bioanalysis of endogenous compounds in cerebrospinal fluid.

Rationale: Research on disorders of the central nervous system (CNS) has shown that an imbalance in the levels of specific endogenous neurotransmitters may underlie certain CNS diseases. These alterations in neurotransmitter levels may provide insight into pathophysiology, but can also serve as disease and pharmacodynamic biomarkers. To measure these potential biomarkers in vivo, the relevant sample matrix is cerebrospinal fluid (CSF), which is in equilibrium with the brain's interstitial fluid and circulates through the ventricular system of the brain and spinal cord.

Discovery of a novel series of quinolone α7 nicotinic acetylcholine receptor agonists.

High throughput screening led to the identification of a novel series of quinolone α7 nicotinic acetylcholine receptor (nAChR) agonists. Optimization of an HTS hit (1) led to 4-phenyl-1-(quinuclidin-3-ylmethyl)quinolin-2(1H)-one, which was found to be potent and selective. Poor brain penetrance in this series was attributed to transporter-mediated efflux, which was in turn due to high pKa.

Phenacetin pharmacokinetics in CYP1A2-deficient beagle dogs.

Phenacetin is widely used as an in vitro probe to measure CYP1A2 activity across species. To investigate whether phenacetin can be used as an in vivo probe substrate to phenotype CYP1A2 activity in dogs, beagle dogs previously genotyped for a single nucleotide polymorphism that yields an inactive CYP1A2 protein were selected and placed into one of three groups: CC (wild-type), CT (heterozygous), or TT (homozygous mutants). The dogs were dosed with phenacetin orally at 5 and 15 mg/kg and intravenously at 15 mg/kg.

Pharmacokinetic-pharmacodynamic modeling of rifampicin-mediated Cyp3a11 induction in steroid and xenobiotic X receptor humanized mice.

The purpose of this study was to develop a mechanistic pharmacokinetic-pharmacodynamic (PK-PD) model to describe the effects of rifampicin on hepatic Cyp3a11 RNA, enzymatic activity, and triazolam pharmacokinetics. Rifampicin was administered to steroid and xenobiotic X receptor (SXR) humanized mice at 10 mg/kg p.o.

Simultaneous bioanalysis of a phosphate prodrug and its parent compound using a multiplexed LC-MS method.

Background: Bioanalytical support of drug-discovery efforts increasingly requires more complex multiple component analysis, including the bioanalysis of drugs, prodrugs and metabolites. Just as the physiochemical properties of these components may differ widely from each other, optimal LC and MS conditions, including polarity, can also vary greatly among the analytes of interest, thus presenting significant challenges during quantitative LC-MS-based bioanalysis. A single compromised method for the determination of all analytes may sacrifice sensitivity or chromatographic conditions for one analyte in order to achieve adequate results for another.

The pneumotoxin 3-methylindole is a substrate and a mechanism-based inactivator of CYP2A13, a human cytochrome P450 enzyme preferentially expressed in the respiratory tract.

3-Methylindole (3MI), a respiratory tract toxicant, can be metabolized by a number of cytochromes P450 (P450), primarily through either dehydrogenation or epoxidation of the indole. In the present study, we assessed the bioactivation of 3MI by recombinant CYP2A13, a human P450 predominantly expressed in the respiratory tract. Four metabolites were detected, and the two principal ones were identified as indole-3-carbinol (I-3-C) and 3-methyloxindole (MOI).

Ion suppression and cannulation locking solutions.

Ion suppression is a common concern when utilizing liquid chromatography-tandem mass spectrometry for quantitation of analytes in biological samples. Ion suppression can cause the analytical signal for the analyte and/or the internal standard to be reduced compared with prepared analytical standards, leading to erroneous quantitation values for the desired analyte of interest. While it has become commonplace to note ion suppression due to the dosing vehicle in in vivo experiments, we have observed a similar phenomenon of ion suppression due to the components of the locking solution used to keep the cannula patent in certain rodent experiments.

Quantitative relationship between rifampicin exposure and induction of Cyp3a11 in SXR humanized mice: extrapolation to human CYP3A4 induction potential.

The SXR humanized mouse model was used to quantitatively assess an in vivo induction response of the human PXR agonist, rifampicin. Three days of rifampicin treatment increased RNA expression and microsomal enzyme activity of CYP3A11, as well as significantly reduced triazolam plasma exposure. These results indicate that the humanized SXR mouse can be used as a model to predict human CYP3A4 induction and the resulting pharmacokinetic changes of CYP3A4 substrates in humans.

Development and validation of a preclinical food effect model.

A preclinical canine model capable of predicting a compound's potential for a human food effect was developed. The beagle dog was chosen as the in vivo model. A validation set of compounds with known propensities for human food effect was studied.

Identification of a nonsteroidal liver X receptor agonist through parallel array synthesis of tertiary amines.

A potent, selective, orally active LXR agonist was identified from focused libraries of tertiary amines. GW3965 (12) recruits the steroid receptor coactivator 1 to human LXRalpha in a cell-free ligand-sensing assay with an EC(50) of 125 nM and profiles as a full agonist on hLXRalpha and hLXRbeta in cell-based reporter gene assays with EC(50)'s of 190 and 30 nM, respectively. After oral dosing at 10 mg/kg to C57BL/6 mice, 12 increased expression of the reverse cholesterol transporter ABCA1 in the small intestine and peripheral macrophages and increased the plasma concentrations of HDL cholesterol by 30%.